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From: Blaisorblade <blaisorblade@yahoo.it>
To: user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] Re: [PATCH 12/16] UML - Memory hotplug
Date: Sat, 25 Mar 2006 00:58:57 +0100
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Cc: Andrew Morton <akpm@osdl.org>, Jeff Dike <jdike@addtoit.com>,
       linux-kernel@vger.kernel.org
References: <200603241814.k2OIExNn005555@ccure.user-mode-linux.org> <20060324144535.37b3daf7.akpm@osdl.org>
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On Friday 24 March 2006 23:45, Andrew Morton wrote:
> Jeff Dike <jdike@addtoit.com> wrote:

> > Unplugged pages are allocated and then madvise(MADV_REMOVE), 

> > This patch also removes checking for /dev/anon on the host, which is
> > obsoleted by MADVISE_REMOVE.

>  * NOTE: Currently, only shmfs/tmpfs is supported for this operation.
>  * Other filesystems return -ENOSYS.

> Are you expecting that this memory is backed by tmpfs?

Yes, that's the recommended configuration, and we're going to move the default 
position for the backing file to /dev/shm.

However, it's bogus to miss any error handling - possibly not returning err is 
wanted (dunno) because Jeff wants to pretend it succeeded anyway, but at 
least a printk() to inform the user that memory must lay on tmpfs is 
required.

> +int os_drop_memory(void *addr, int length)
> +{
> +     int err;
> +
> +     err = madvise(addr, length, MADV_REMOVE);
> +     if(err < 0)
> +             err = -errno;

Jeff, did you mean the "return _0_" rather than "return err" below? It's 
incoherent with the existance of the "err" local.

> +     return 0;
> +}

-- 
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade

	

	
		
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